Imdb-sqlite

* New flag for skipping index creation

This flag cuts the DB size in half approximately, but it also means joining columns will be unusably slow. That is unless you create your own indices manually. See readme for the rationale.

* Performance improvement that affect joining tables.
* The index creation step now provides a progress bar.

Note, an additional index was introduced on people to make the README example orders of magnitude faster. The downside is that this index takes up some additional space.

Stable release 🎉

5 years in pre-release is enough.

Changes:
* **Fix spelling of column `episodes`**
Note: This is a breaking change in case you depended on the typo (eposides).
Closes 3
* **Readme updated with schema diagram and query examples**
Note: foreign key constraints are _not_ defined nor enforced, even though depicted in the diagram. Foreign keys are not used, as a safe-guard against bad data from IMDB that may violate the constraints. Better to get whatever data IMDB offers into the DB than be picky about relations enforcement.
Closes 2

Fixes:
* Invalid data type used for ID schemas (integers where they should have been strings)
* Null (`\N`) characters not replaced with DB nulls. Happened when the imdb null-characters occurred in the last column of a TSV file.